Two cars leave the city on the same road, one driving 12mph faster than the other. After 4 hours, the car travelling faster stops for lunch. After 4 hours and 30 minutes, the car travelling slower stops for lunch. Assuming that the person in the faster car is still eating lunch, the cars are now 24 miles apart.
Car 1 drives at V1 mph
Car 2 drives at V2 = V1 + 12
After 4 hrs, distance travelled by car 2 (faster car) is S2 = 4*V2 = 4(V1 + 12)
S2 = 4V1 + 48
After 4 ½ hrs, distance travelled by car 1 (slower car) is S1 = 4.5*V1
S1 = 4.5V1
Distance between cars is 24 miles,
S2 – S1 = 24
4V1 + 48 – 4.5V1 = 24
-0.5V1 = -24
V1 = 48 mph
V2 = 60 mph